package org.magic.cloud.common.poi.impl.column;

import static com.google.common.base.Preconditions.checkArgument;

/**
 * Created on 02/04/13
 *
 * @author d.serdiuk
 */
public class Columns {
	private static final int OFFSET_TO_A = 64;

	public static String columnIndexAsLetters(int index) {
		checkArgument(index > 0, "index must be positive");
		checkArgument(index <= 702, "only 702 columns supported now");

		int first = index / 27;
		int second = index - first * 26;

		String firstChar = first == 0 ? "" : String.valueOf((char) (first + OFFSET_TO_A));
		char secondChar = (char) (second + OFFSET_TO_A);
		return firstChar + secondChar;
	}
}
